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Special Folders and the 'path to' command

Introduction

The path to command from the Standard Additions osax provides a fully portable mechanism for determining the location of special folders in the system. The line below will return an alias to the Scripting Additions folder on whatever machine is running it, regardless of the name of the volume/disk or the system language:

path to scripting additions
--> alias "MacHD:System:Library:ScriptingAdditions:" -- under OS X
--> alias "MacHD:System Folder:Scripting Additions:" -- under OS 8/9

The Standard Additions dictionary has never, as of this writing, provided a full list of the folders for which human language terms exist. That list, shown below, is itself a subset of the folders whose paths can be obtained using the path to command. This table was derived from Folders.h, a C header file found here on my machine. If you run OS X, clicking the link should reveal or open your own copy, depending on your browser settings.

The full list of folders is available by calling path to using four character codes from the table below. This produces the same result as the line above:

path to "ƒscr"

OS X also offers an extra parameter for path to, which takes into account the fact that there can be up to 4 versions of each special folder:

path to "ƒscr" from System domain
--> alias "MacHD:System:Library:ScriptingAdditions:" -- the default, which doesn't make much sense given that it's read only

path to "ƒscr" from local domain
--> alias "MacHD:Library:ScriptingAdditions:" -- scripting additions available to all users

path to "ƒscr" from user domain
--> alias "MacHD:Users:username:Library:ScriptingAdditions:" -- scripting additions available only to the current user

The fourth option (prior to AS 1.9.2, which shipped with 10.3) is from network domain, which I can't test. Check the Standard Additions Dictionary for the list.

AS 1.9.2 added a fifth option - from Classic domain - which allows access to the special folders in the nominated classic System Folder and the new option of not creating folders if they don't already exist.

Other Info

Returning Strings

It is common to use the result of a call to path to to build a path string, which requires a coercion to string from alias. This can be done in the usual way, but the command can return a string itself and this is measurably faster than a coercion:

path to "ƒscr" as string
--> "MacHD:System:Library:ScriptingAdditions:"

From somewhere around AS 1.8.3. or so, it is also possible to return the path as Unicode text.

Raw Event Syntax

It is also possible, though probably not necessary, to use AppleScript's raw syntax:

path to «constant ****pubb»
--> alias "Mac HD:Users:username:Public:"

This syntax will compile to a human understandable term if one exists:

path to «constant ****pref»

Compiles to:

path to preferences

Other Uses

As well as providing machine independent paths, path to has a few other functions:

path to me

The result of this varies depending on the context. If used in a script application, it will return the full path to the application, including its name. If used in Apple's Script Editor, it will return the path to the editor. Other editors, such as Script Debugger, allow it to return the path to the calling script. Apple's Script Menu returns the path to the System Events app, which is the process that runs all Script Menu scripts.

The main use for this command is to find resources that are in a known location relative to a script application. I've used it in installers for example.

It is also possible to use it to return the path of the current application:

path to current application

The result also varies depending on the context. I've used it in an application to get the name of the frontmost app in classic MacOS, but Script Editor (2.0b) will only return the path to itself, even after another app has been activated, so the behaviour may have changed in OS X.

Folder Table

Legend

Description is the comment from the header file
Full Form shows the human language term where applicable (tested under OS 10.2)
Code is the four character code that can be used in quotes, as shown above
Result under... show the resulting paths (strings are shown, but they're actually aliases) as they are on my machine

Errors:
(1) "Disk some object was not found" (number -35) -- misleading error from AS 1.4/OS9.0.4
(2) "Folder is not available in this operating system version." (number -43) -- OS X
(3) "Folder does not exist, and you don't have access privileges to create it." (number -5000) -- OS X

Notes

Be aware that AppleScript versions prior to 1.9.2 (OS 10.3) will create the folders called by the command if possible and if they don't already exist. This can lead to some whacky things, such as a 'Recent Applications' folder being created in the current user's folder in OS X if path to "rapp" is called. AS 1.9.2 added the boolean folder creation, which defaults to true for backward compatibility. If path to is called using without folder creation it returns error number -43 if the folder does not exist.

Not all of the OS X defaults make sense - path to "apps" - creates an 'Applications' folder in the current user account, instead of returning the main Applications folder, though it can be obtained by adding the from local domain parameter.

Kudos to the creative individual who created the Location Manager codes.

The FooDoo Lounge is Copyright © Richard Morton 2002-2005

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